Free tool · no login required
GST Calculator
Add GST to an amount, or work backward to find the tax already inside a GST-inclusive price — across the standard 0/5/12/18/28% slabs, with the CGST+SGST or IGST split shown automatically. Nothing you type here leaves your browser.
What this calculator does not do
This only computes the CGST/SGST/IGST split on a single amount — it does not generate an invoice, does not create an e-invoice/IRN, does not connect to the GST e-invoicing portal, and nothing you type here is saved or sent to any server.
Need a full GST invoice instead?
Try the free GST invoice generator, or let Biller compute and print GST on every bill automatically — free to start, no credit card.
Try Biller freeFrequently asked questions
Is this GST calculator really free?
Yes — no login, no signup, and no limit on how many times you use it.
"Add GST" vs "Remove GST" — what's the difference?
"Add GST" treats your amount as the price before tax and adds GST on top. "Remove GST" treats your amount as a price that already includes GST and works backward to find the taxable value and the tax already inside it.
How does it decide CGST+SGST vs IGST?
Same state means CGST + SGST, split equally; a different state means a single IGST line — the standard GST place-of-supply rule, the same choice a real invoice makes.
Does this generate an invoice or file anything with the GST portal?
No — this only computes the tax split on one amount. It does not generate an invoice or an e-invoice/IRN, and does not connect to the GST e-invoicing portal.